1. Field of the Invention
The present invention relates to a method and apparatus for automatically cutting a packaging material wrapping of a substantially parallelepipedic package at a predetermined position thereof and opening the package, the package being formed by wrapping packaged items in the packaging material in such a way that the package has a pair of bonded flaps at each of at least three adjacent faces thereof.
2. Description of Background Art
There are rectangular paralelpiped-shaped paper containers for liquid foodstuffs, e.g. milk or juice, such as that shown in FIG. 19. Such a paper container blank 2 is folded flat as shown in FIG. 20 so that it will not be bulky when stored. Then, as shown in FIG. 1, a large number of paper container blanks 2 are put together and wrapped in a bundle with a packaging material 3 so as to be stored in the form of an approximately parallelepipedic package 1. The package 1 is opened when the paper container blanks 2 are used to fill a liquid foodstuff, or the like, thereinto.
The package-opening operation has heretofore been performed by hand under normal circumstances. That is, the steps of cutting the packing material at a predetermined position thereof, opening the package, and taking out the paper container blanks are usually carried out by a manual operation.
However, a machine is used to perform all the operations of unfolding each flat-folded paper container blank into a rectangular parallelpiped shape, forming a bottom of the paper container blank, filling it with a liquid foodstuff, or the like, and sealing the paper container. Therefore, a great deal of labor is required to open each package by a manual operation in conformity to the machine operation. Thus, the manual package opening operation is inefficient.
To solve the inefficiency problem, a method has been proposed in which the packaging material is mechanically cut to open the package by using a cutting blade [for example, see U.S. Pat. No. 5,048,267 and Japanese Patent Application Unexamined Publication (KOKAI) Nos. 62-271827 and 62-271828]. However, the package 1 is in such a condition that there is substantially no gap between the packaging material 3 and the packaged items 2, which are paper container blanks. Therefore, if a cutting blade is carelessly applied to the packaging material 3, the packaged items 2 may be damaged, resulting in a failure fatal to paper containers, e.g. ultimate leakage of liquid.